Describe the useful action before listing screens: a customer checking a service request, a colleague recording work or an account holder completing a repeated task. We map how that action starts, what information it needs and what the business does with the result. That gives design and development a shared purpose.
A commission may cover a new customer app, an internal application or an improvement to an existing product. We compare an installed app with a responsive web journey, then agree the platforms and implementation approach around the actual requirements. Existing source, accounts and interfaces need inspection before a replacement or integration is estimated.
The first release should provide a coherent journey, including an understandable correction or unsuccessful outcome. Extra platforms, payments, offline work and device features belong in the proposal when they serve that journey; they are not assumed from a design mock-up.